The purpose of this investigation is to gain understanding of the interrelationships between various elements of the immune response to respiratory viruses which lead to protective or to harmful effects. The study will develop immunizing strategies to Sendai virus and respiratory syncytical virus which will evoke a response to only one or two antigens of these viruses. This will be accomplished by isolating and purifying the surface glycoproteins of the viruses and reconstituting them separately or in combination into lipid vesicles. The strategies will evoke the restricted antibody responses either in the serum or in the secretions or both as well as evoking systemic and local cell-mediated immunity. This will be done by immunizing the animals either parenterally or through the mucosa, each route with and without adjuvants. Animals immunized with these strategies will have different profiles of response to the viruses. Such animals with different responses will be challenged by the respiratory route with live virus and their response to the challenge observed. The degree of protection or harm will be ascertained by quantifying the amount of virus shedding in the challenged animals, determining the type of pathology and observing the morbidity and mortality among the animals.